Ask watch enthusiasts for advice on choosing a tough, reliable tool watch, and there’s one brand you’ll almost always hear suggested: Sinn. The German brand has gained a sterling reputation for its purpose-built watches, many of which have been designed in direct collaboration with military and professional organizations for use and abuse in the field. Over the years, Sinn has developed myriad technological innovations that allow its watches to be used in some of the harshest conditions on earth. In particular, the EZM (Einsatzzeitmesser, or mission timer) series of watches is a line of watches purpose-built for professional applications and loaded with Sinn’s proprietary tech. Within the EZM lineup, you’ll find the Sinn EZM 13.1 dive chronograph. The EZM 13.1 isn’t a completely new watch in Sinn’s catalog, but it might as well be. One small, seemingly insignificant change to the now-discontinued EZM 13 — removing the Arabic numerals — has completely transformed the personality of this “destro” chronograph, resulting in a mission-built dive watch that is as clean, legible, and as tough as ever. Thankfully, our friends over at J. Vair Anderson in Calgary were able to send one over so we could see how it stacked up.

The Sinn EZM 13.1 clocks in at 41mm in diameter and 47.5mm lug-to-lug. Though not unexpected for a 500m water-resistant chronograph, the EZM 13.1 is rather chunky at 15mm in height. Like a slimming shirt, however, Sinn’s managed to hide the extra girth surprisingly well. Sinn utilizes a sloping bezel and a (relatively) slim midcase, both of which help reduce the perceived height of the watch. The short and steeply sloping lugs help the EZM 13.1 sit comfortably and securely on the wrist, while the crown and pushers placed on the 9 o’clock side of the case ensure that those elements never dig into your wrist. These details may seem minor, but together they help the watch look, and wear, smaller than you might expect. That’s not to say the EZM 13.1 feels small, but rather that it fits more comfortably and is more manageable than expected for those with smaller wrists (for reference, my wrist is 6.75”).

The quality and construction of the EZM 13.1 are exactly what we’ve come to expect from Sinn — solid, no-frills, and extremely high-quality. The finish is bead-blasted and, while there are chamfers on the lugs, you won’t find mixed surface finishing or complex lines. This is a tool watch through and through. What you’re paying for with Sinn isn’t the finishing, but the overall construction and thoughtful design. Atop the case is a unidirectional captive bezel held in place with a series of screws. The bezel turns firmly with a solid, workman-like click; there’s no back-play and each of the 60 clicks is precise and secure. Similarly, the chronograph pushers have a solid, reassuring engagement that mirrors the purpose-built feel of the bezel. Finally, the signed crown winds smoothly and is easy to engage.

The Sinn EZM 13.1 runs on the brand’s SZ02 caliber. Starting with a Valjoux 7750 movement, Sinn has made several important modifications in order to give the EZM 13.1 its distinct look and functionality. First, the movement was rotated 180 degrees in order to place the crown and pushers on the left side of the case and also allow Sinn to display the minute counter (modified to display a full 60 minutes) at 6 o’clock. Sinn then removed the hours counter and shifted the running seconds to 3 o’clock. Finally, Sinn finishes off the EZM 13.1 with a red-on-black date window tucked in at 4:30.

The most striking aspect of this chronograph is how cleanly it reads. Some enthusiasts are put off by chronographs — especially dive chronographs — because they can feel cluttered or overly busy. Not so with the EZM 13.1. First and foremost, the time-telling is instantaneous, the 60-minute register is the only element that could possibly interfere with legibility. But, thanks to its position and layout, the register never feels intrusive. Similarly, the running seconds is as minimal as it gets, the dark gray minutes track blending seamlessly with the dial, the seconds hand serving simply as an indication that the watch is running. One element that may be slightly divisive will be the red-on-black date wheel, as it’s certainly harder to read the date than a white-on-black date. However, fans of no-date watches will love the fact that the date is so unobtrusive and easy to ignore, just a touch of red playing off the other small red accents on the dial, like the Ar symbol at 9 o’clock (indicating the use of the brand’s dehumidifying technology) and EINSATZZEITMESSER tucked under the Sinn logo.

Fans of Sinn watches will often point to the brand’s technology as a major selling point. With the EZM 13.1, you get some but not all of that vaunted tech. For instance, the EZM 13.1 uses the brand’s Ar-Dehumidifying Technology, which includes filling the case with inert gas and the use of a copper sulfate capsule inserted into the side of the case at 1:30. So, even if some moisture should sneak in, the copper sulfate capsule will absorb the moisture, turning the copper sulfate darker blue when it’s time to replace the capsule. In addition, the EZM 13.1 sports 80,000 A/m of anti-magnetism, temperature resistance from -45°C up to +80°C, a captive bezel, and Sinn’s D3-System that allows the user to operate the chronograph functions while the watch is submerged. And, of course, the watch is water-resistant to 500m, meets the DIN 8310 standard, and is certified to the European diving standards EN 250 / EN 14143.

That’s a long laundry list of tech, but there’s one piece missing: tegiment. Many of Sinn’s watches utilize Sinn’s tegiment, or surface-hardening, process but unfortunately, that’s not an option with the EZM 13.1. Given that the watch has just about every other wild piece of Sinn tech, a tegiment version, even with the concomitant upcharge in price, would be a nice option. And, since we’re creating a wish list, drilled lug holes would also be welcome.

The H-link bracelet on the Sinn EZM 13.1 is a bit of a mixed bag. The smooth edges and excellent articulation make the bracelet a pleasure to wear. Plus, the look of these bracelets is now synonymous with Sinn and certainly fits the aesthetic of the EZM 13.1. The downside with Sinn’s H-link bracelets is the clasp. In terms of function and comfort, there’s absolutely nothing wrong with the clasp, but now that machined clasps with on-the-fly, tool-free micro-adjustments are often found in watches costing a fraction of the price, the simply stamped clasp is a bit of a let-down. The bracelet does have 3 holes for micro-adjustment and a dive extension. That said, Sinn also offers the EZM 13.1 on its extremely comfortable silicone strap, complete with a machined push-button clasp. Given the military vibe of the EZM 13.1, it’s also hard to go wrong with a NATO-style strap or something like the Erika’s Originals MN strap (as pictured), especially if you’re looking to decrease weight and bulk for outdoor activities.

The Sinn EZM series of watches are quintessential tool watches: tough, legible, and packed with tech. With one small, superficial change to the EZM 13, the EZM 13.1 has become much more legible and versatile. If you’re after a chronograph with a clean, purpose-built aesthetic, the EZM 13.1 certainly fits the bill. That said, if the styling appeals to you, but you want a thinner watch without the chronograph functionality, Sinn also offers the EZM 3F. The Sinn EZM 13.1 is priced at $3,270 USD on bracelet. To learn more about the EZM 13.1 and other Sinn watches, please visit the brand’s website.

Necessary Data
>Brand: Sinn
>Model: EZM 13.1
>Price: $3,270 on bracelet
>Size: 41mm diameter, 15mm height, 47.5mm lug-to-lug, 20mm lug width
>When reviewer would personally wear it: On outdoor adventures and anytime I’m looking for a nearly indestructible watch.
>Friend we’d recommend it to first: Someone looking for an incredibly tough chronograph with Sinn’s distinctive EZM design language.
>Best characteristic of watch: Cohesive design coupled with Sinn’s top-notch tool watch construction and tech.
>Worst characteristic of watch: Though it hides its girth well, this is still a thick watch at 15mm. A tegiment option would be welcome.